ISO 23611-4:2007 specifies a method for sampling and handling free-living nematodes from terrestrial field soils as a prerequisite for using them as bio-indicators (e.g. to assess the quality of a soil as a habitat for organisms).
ISO 23611-4:2007 applies to all terrestrial biotopes in which nematodes occur. It is not applicable to aquatic nematodes because these nematodes do not pass through the filter.